Draft regulator



H. FRENTZEL; JR

July 75, 1938;

I DRAFT REGULATOR Filed Nev. 9, 1935 2 SheetsSheet l BY I ATTORNEYS.

INVENTOR.

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ATTORNEY.

July 5, 1938.

H. C. FRENTZEL, JR

DRAFT REGULATOR Filed NOV. 9, 1935 2 Sheets-Sheet 2 V Patented July 5, 1938 PATENT OFFICE.

DRAFT REGULATOR Herman 0. Frentzel, Jr., Milwaukee, Wis., assignor to The Hell 00., Milwaukee, Wis., a corporation of Wisconsin Application November 9, 1935, Serial No. 48,960

. 4 Claims.

l'he present invention relates generally to improvements in the art of heating, andrelates more specifically to'improvements in the construction and operation of draft regulators for .5 controlling the quantity of combustion air admitted to the fuel chambers of furnaces, boilers or the like.

A general object of the present invention is the provision of an improved draft regulator which is extremely'simple in construction, and

which is moreover automatic, reliable and highly eilicient in operation.

It is a well established fact that the efliciency of a heating plant is materially affected by undesirable variations in the quantity of air delivered to the fuel combustion chamber, as a result of draft variations. Automatic and accurate draft regulation is therefore desirable in order to maintain most eflicient combustion and to avoid excessive heat losses through the stack, and numerous types of automatically functioning draft actuated control devices associated either with the smoke pipe or with the stack, .have heretofore been proposed. With some of these prior draft regulators, more or less fresh air-from the furnace room is admitted to the smoke and gas conducting conduit of the smoke pipe or stack, without actually varying the normal cross-sectional area of this conduit; while in others the conduit cross-section is varied without admitting additional air thereto. Both of these prior types possess some advantages as well as disadvantages, and under certain conditions of operation it would appear advantageous to combine these prior methods of control-so 'as to secure the benefits of both.

It is therefore a more-specific object of the pres- .ent invention to provide an improved automatic 1 damper which effectively combines the principles of operation of these two prior types of regulators, and 'wherein both throttling and admission.

of furnaces and boilers, and which is capable of convenient and sensitive adjustment so as to secure any desired operation.

Still another specific object of the invention is the provision of an improved draft regulator especially applicable to oil fired combustion chambers, which is exceptionally reliable in op- .eration and which can be manufactured and installed at moderate cost.

An additional specific object of the present invention is to provide a damper associable directl0 ly with the gas discharge end of a fuel combustion chamber, and which fuhctions to simultaneously vary the cross-sectional area of the combustion gas discharge conduit, and to introduce inversely proportional variable quantities of ambient air to the smoke pipe beyond the combus tion gas discharge opening. I

These and other objects and advantages of the present improvement will be apparent from g the following detailed description.

A clear conception of several embodiments of .the invention, and of the mode of constructing and of utilizing draft regulating appliances built in accordance with the improvement, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the several views.

Fig. .1 is a fragmentary part sectional side elevation of a heating plant comprising a fire-tube boiler, smoke .pipe and stack, showing one of the improved regulators associated with the boiler and smoke pipe;

v Fig. 2 is a fragmentary rear view of the boiler of Fig. 1, looking toward the draft regulator;

Fig. 3 is an enlarged internal front view of the draft regulator shown in Figs. l and 2;

Fig. 4 is a further enlarged vertical-section through the draft regulating unit, taken along the line 4-4 of Fig. 3;

Fig. 5 is a similarly enlarged fragmentary internalfront view of a lower corner of the unit of Figs. 3 and 4; and

Fig; 6 is a vertical section similar to that of Fig. 4, through a modified type of the improved 45 draft regulating unit.

While the invention has been illustrated herein as being specifically embodied in a heating plant having a boiler of the fire-tube type, it is not intended to unnecessarily restrict the scope by 50 such embodiment, since the improvement is obviously more generally applicable to other types of furnaces and combustion chambers.

Referring to the drawings, the heating system shown. in Figs. 1 and 2, comprises in general a '56 boiler 8 having a water chamber 8 and a com bustion chamber III, the latter of which communicates with a rear gas discharge space H through fire-tubes |2 penetrating 'the water chamber 9; a chimney or smoke stack 1;! ordinarfiy spaced some distance from the rearof the boiler 8; and a smoke pipe ll connecting the flue of the stack l3 with the boiler space H through a gas discharge orifice l5 formed in a smoke box or fitting l6 secured to the rear of the boiler. All of theseelements are of well known construction and are subject to considerable variationin form and location, and the combustion chamber iii may be fired with any suitable fuel such as coal, coke, oil or gas, being provided with the usual controllable means for injecting or admitting combustion air to the ignition or burning zone.

The fitting I6 which is secured to the rear of the boiler 8 and widen provides a closure for the gas space H, has a rearwardly extending con-,

' l9 and integral laterally spaced ferwardlly projecting parallel side walls 20 extending into the space H; and a fiat plate-like damper 2| mounted to swing between the walls 20 upon alined end pivots 22 carried by the damper 2| and coacting with bearings 23 secured to the closure member it, see Figs. 2, 4 and 5. The member Ill-has a peripheral recess 24 which is cooperable with the 'rearedge of the flange i1, and is swingably suspended, from the fitting l6 by hinges 25, being a normally held in closed position by a latch 26 as shown in Fig. 2. A eurved wall 21 formed integral with the member l8, extends upwardly from the lower edge of the opening i9 to the;

tively thin sheet metal, and the alined suspension pivots 22 for this damper are carried by blocks 28 secured to the medial-portions of the opposite ends of thedamper, the common, axis of the pivots 22 being disposed forwardly of the plane of the damper. The upper portion of the damper 2| is automatically swingable about the pivots. 22

' between the parallel side walls 20, from closed position as shown in solid lines in Figs. 1 and 4, to open position as shown in dot-and-dash lines, by the differences in pressure acting upon the 'upper portion of the damper plate and caused by variations in draft conditions. when completely closed, the upper portion of the damper 2| coacts 'with a sealing strip 29 secured to the supporting with a central stud 30 secured thereto between plate is disposed rearwardly of its horizontal piv= otal axis and that the fixed stud 30 also extends rearwardly with respect to this axis, the ofi-set centersofgravity of these parts would normally tend to swing the damper 2| toward the sealing gravity located forwardly of the pivotal axis, the

weight being of such heft that, static balancing of the pivotally suspended elements, other than the adjustable weight 32 and nut 33,- results.

With this assembiage of elements, it will. be apparent that when the-adjustable weight 32 is located as near to the damper 2| as possible, the letter will be easily shifted by slight variations in pressure acting on opposite sides of the upper portion thereof, whereas adjustment of the weight 32 away from the plane of the damper will require increased pressure acting upon the rear surface ofgthe same in order to swing it away from the sealing strip 29.

During normal operation of the improved draft regulator of Figs. 1 to 5 inclusive, and when fuel is being consumed in the combustion chamber iii of the boiler 8, hot gases of combustion are being delivered from the fire-tubes through the space H, orifice l5 and smoke pipe I4, to the stack l3. Depending upon the setting of the mechanism for supplying combustion air, a pre-' determined quantity or volume of gases of combustion will normally flow through these passages to the stack I3, but any variations in draft condtions will tend to undesirably increase or decrease the quantity of combustion air and will thus tend to reduce the efiiciency either by causing incomplete combustion or by overheating the liquid. The improved draft regulator may be conveniently and accurately set'by adjusting the weight 32 through the opening 59, so as to automatically produce any desired condition of operation; When the weight 32 has been properly adjusted to correspond with a predetermined setting of the fuel and fresh air supply, the damper 2| will automatically adjust itself by swinging upon its supporting pivots 22, so as to simul= taneously throttle the area of the passage between the space H and orifice l5, and to admit sufiicient ambient air through the opening l9 directly to the smoke pipe it through the orifice l5, to meet the changing draft conditions within the stack i3, without undesirably affecting the quantity of combustion air admitted to the chamber I0. If the stack draft increases, the throttling effect upon the flow of gases of cembustion will be increased and more air will be admitted through the opening !9, and vice versa; but the communication between the space H and orifice i5 can neverbe entirely interrupted. When the boiler is not in use, the damper 2| will automatically close by engaging the sealing strip 29, and v the weight 32 may obviously be quickly and conveniently adjusted to secure any des red condi- Fig. 4, but is somewhat different in principle of operation. In the modified assemblage, the plate damper 2| is provided with an arcuate sealing flange 36 at the upper swinging end thereof, and the supporting member I! has a rear bulge 31 above the opening I8 for accommodating the swinging motion of the flange 36. The counterbalancing weight 35' is slightly enlarged to compensate for the addition of, the flange 36, and this flange is adapted to maintain substantially constant sealing cooperation with a lip 38 formed upon the member i8 while the sides of the damper 2 I have like cooperation with the parallel side walls 20 for all positions of adjustment of the damper plate. The modified dapperfl is adapted when closed, to seat against sealing strips 29 carried by the member l8, but should be freely swingable without excessive friction, upon its pivots 22, as in the case of the damper 2|.

During normal operation of the modified draft regulator of Fig. 6, the damper 2| will again swing back and forth about its pivots 22, as the draft in the heating system varies, but this damper will exercise only a throttling effect upon the gases of combustion, and will not admit ambient air through the opening i9 to the smoke pipe or stack. The ambient air within the furnace room will merely act upon the rear surface of the damper 2! to create a pressure'thereon,

' and as the stack draft varies, this pressure will cause the damper plate and the fiange 36 to move back and forth and to thereby vary the effective area of the orifice I5 leading to the smoke stack. The adjustable weight 22 ofthe modified device functions preciselyv the same as previously described, and when the combustion of fuel ceases, the modified damper 2U will close by engaging the sealing strips 29'.

From the foregoing description itwill be apparent that the present invention provides an automatic damper or draft regulator which is extremely simple, compact, and durable in construction, and which is moreover highly eilicient and reliable in its operation. The draft regulator may be readily applied as a unit to any type of combustion chamber and may be conveniently adjusted to produce any desired predetermined operation. The various elements of the improved assemblage are thoroughly protected the pivots 22 and of the bearings 23. While the combined'throttling and air admitting type of draft regulator shown in Fig. 4 is thoroughly satisfactory in most heating installations, it may be undesirable to withdraw air from the furnace room in eifecting the regulation, and under such conditions the draft regulator of Fig. 6 may be more desirable. The improved draft regulating units can be readily constructed without exces-' sive machining operations, and can therefore be manufactured-and sold at moderate cost. The invention has proven highly successful in actual operation, especially when applied to oil burning heating plants, and has demonstrated its ability to insure minimum waste of heat.

It should be understood that it is not desired Q to limit the invention to the exact details of construction and to the precise mode of operation herein shown and described, for various modinot from the outside through HERMAN fications within the scope of the claims may ocour to persons skilled in the art.

I claim:

1. A draft regulator for a combustion chamber,

comprising, a pivotally suspended closure memdamper having a balancing weight suspended therefrom within the outlet end of the combustion. chamber, and an adjustable regulating weight carried by said damper within said member and between said side walls, said regulating weight being constantly accessible for adjustment through said opening.

2. A draft regulator for a combustion chamber, comprising, a removable closure member for the outlet end of the combustion chamber, said member having a lower opening shielded by a wall formed integral with said member and also having integral side walls extending upwardly from said shielding wall and from said opening and into the combustion chamber, a damper pivotaliy suspended from said member near the inner end of said shielding wall and swingable between said side walls to control the admission of air through said opening, and adjustable regulating means for said damper housed within'said member and constantly accessible for adjustment through said opening.

3. A unitary draft regulator for a combustion chamber, comprising, a closure member for the outlet end of the combustion chamber, said member having an opening communicating with the atmosphere and integral parallel side walls extending upwardly away from said opening, a damper plvotally suspended from saidmember and swingable between said walls to control the admission of air through said opening, said damper having a balancing weight fixedly at-- tached thereto within said combustion chamber, and an adjustable regulating weight carried by said damper within said member and between said side walls, said regulating weight being accessible for adjustment from the outside through said opening. i

4. A unitary draft regulator for a combustion chamber, comprising, a closure member for the outlet end of the combustion chamber, said member having an opening shielded by a fixed wall pivotally suspended from said member near the inner end of said fixed wall and swingable between said side walls to control the admission of air through said opening, and adjustable regulating means for said damper housed within said member and being accessible for adjustment said opening.

0. mm, Jr. 

